Double exposure prevention device



Feb. 12, 1946. M. R. HUTCHISON, JR 2,394,614 I DOUBLE EXPOSUREPREVENTION DEVICE Filed NOV. 16, 1944 FIG].

FIG. 23% FIG. 8.

36 45 32 26 3 20 FIG 9. MILLER R.HUTCHISON, JR.

" A INVENTOR L W BY 75 L 136 Z ATTORNEYS Patented Feb. 12, 1946 UNITEDSTATES PATENT orncs DOUBLE EXPOSURE PREVENTION DEVICE Miller R.Hutchison, Jr., Rochester, N. Y., assignor to Eastman Kodak Company,Rochester, N. Y., a corporation of New Jersey Application November 16,1944, Serial No. 563,700

12 Claims.

This invention relates to photography and more particularly to a meansfor preventing double exposures upon film carried by a roll holdingcamera. One object of my invention is to provide a simple form ofmechanism which consists of few and inexpensive parts and which may bereadily assembled by relatively unskilled help. Another object of myinvention is to provide a mechanism connecting a, shutter trigger and afilm winding key post by which the trigger will be locked against asecond actuation until film has been Wound. Other objects will appearfrom the following pecification, the novel features being particularlypointed out in the claims at the end thereof.

In my copending application for Double exposure prevention camera,Serial No. 535,511, filed May 13, 1944, now Patent 2,367,504, grantedJanuary 16, 1945, I have disclosed a double exposure prevention devicein which there is a pair of scissor-like arm for accomplishing thedesired locking of the trigger until a fresh film is wound into place.My present invention is for an improvement over the device shown in mycopending application. I have somewhat simplified the structure showntherein and have produced a double exposure prevention device which canbe successfully operated in an extremely restricted area. Certain otherimprovements will appear from the following specification. 4

Coming now to the drawing wherein like reference characters denote likeparts throughout:

Fig. 1 is a top plan view of a camera including a double exposureprevention device constructed in accordance with and embodying apreferred form of my invention. In this figure a cover plate has beenremoved from the top of the camera;

Fig. 2 is a section taken on line 2-2 of Fig. 1 with the parts arrangedin a trigger latching position;

Fig. 3 is a fragmentary view simila to Fig. 1 but with the parts in aposition in which the trigger is unlatched and is ready for operation;

Fig. 4 is a fragmentary sectional view taken on line 4-4 of Fig. 3;

Fig. 5 is a view similar to Fig. 3 but with the parts in a triggerlatching position;

Fig. 6 is a view similar to Fig. 4 but with the trigger depressed into ashutter-operating position;

Fig. '7 is an enlarged fragmentary sectional view taken on line |--'l ofFig. 2;

Fig. 8 is an enlarged fragmentary detail showing a portion of one of thslidable members; and

Fig. 9 is a view similar to Fig. 8 but showing another embodiment of myinvention.

In the present invention 1 have provided a shutter trigger lockingmechanism in which the locking members consist of two simple slidemembers which may be bent up from rod stock and which include a portionwhich may slide axially of the rod members and arms extending from theends of the slidable member for engaging the film winding mechanism andth shutter trigger.

More specifically, the camera I shown in Fig. 1 may be of any standardtype which includes a top wall 2 rabbeted around the edge 3 so a toreceive a cover plate 4 which may have a downwardly extending flange 5adapted to fit on the rabbet 3. This provides a shallow, box-likechamber 6 of very little greater width than the normal width of a camerain which the double exposure prevention mechanism may be entirelyenclosed. The cover plate 6 may be held in place as by screws 1.

The camera I may be of the usual type having a supply film chamber 8 anda take-up film chamber 9 adapted to receive a supply film spool and atake-up film spool H. As is customary of cameras of this type, the filmis wound from the spool 10 to the spool I 1 past an exposure aperture.In order to wind the film the take-up spool chamber 9 is provided with akey post 13 which may have the usual key or flange I4 for engaging thewinding slot in the take-up spool H. In addition, this key post isprovided with a cam I5, this cam being keyed to the shaft 13 and turningwith it.

The camera may also be provided with a trigger member I6 having a headI! terminating in a shoulder 18 from which a shaft IQ of somewhatsmaller diameter extends downwardly through the wall 2 of the camera andinto a po sition in which it may operate any known type of camerashutter.

A collar 20 is mounted to slide about the shaft l9 and is normallyspring-pressed upwardly by a spring 2| engaging the underside 22 of thecollar 20 at one end and supported by a metal housing 23 at the otherend. The flange 22 on the collar prevents this fiange from being movedupwardly beyond the position shown in Fig. 2 but permits the sleeve 20to move downwardly when it is engaged by the shoulder I8 on the trig eras illustrated in Fig. 6. The position of the shoulder l8 relative tothe camera wall 2 is such that, unless this shoulder can be depressedbelow the wall 2 as shown in Fig. 6, the shutter cannot be operated.

In order to prevent the trigger from being moved downwardly to its Fig.6 position until film has been wound, I provide mechanism connecting thekey post i3 and the trigger l6 and this mechanism preferably consists oftwo rods 25 and 26. These rods can conveni ntly be made of square wire,although any other suitable material may be used for these two slidablemembers. I prefer to provide turned-over arms 2! and 28 on the ends ofthe slide members 25 and 26, these arms being of suihcient length toengage the cam I5. A spring 29 fastened between the arms 2'! and 28always tends to move these arms into contact with the cam [5.

At the opposite ends of the arms 25 and 23 I provide arms 3| and 32which are adapted to engage the shutter trigger |5 and/or the sleeve 23.

In order to guide the rods and 26 for their sliding movement I prefer toprovide two supporting members 34 and 35. Member 34 is provided withapertures 36 which are of such a size that the rod 25 may twist or turnin these bearings. Support is provided with apertures 31 which alsopermits sliding of the rods '25 and '26. Because of the confined spacebetween the cover 4 and camera wall 2 the chamber 6 does o D8 mit theends 2'1 and 28 to turn without striking the cover 4. Therefore, turningmovement of the ends 3| and/or 32, permitted by forming 45, tends todistort the rods 25 and 26 from a normal position to which they willtend to return.

It will be evident that, since the ends of the rods 21 and 28 adjacentthe winding key post H! are held against turning any material distanceand since the opposite ends of these rods may be turned, the end of therods 3| and 32 may move up or down a short distance. The normal shape ofthe rods is such that the ends 3| and 3?. will both have a position ofrest in which they may lie fiat against the camera wall 2, as best shownin Figs. 3 and 4. However, when these ends 3| and 32 are engaged betweenthe shoulder ll! of the trigger and the sleeve 29 they may be movedupwardly as indicated in Figs. 2 and '7, and when this movement takesplace a twist or torsional movement is given to the rods 25 and 26, thuseffecting a light spring pressure on the rods tending to turn them totheir normal position of rest flat against the wall 2 as shown in Fig.3.

With the apparatus as thus far described it will be obvious that whenthe parts are in the Figs. 3 and 4 positions the trigger |6 may bedepressed to make an exposure. As the shoulder 58 is lowered it engagesthe sleeve 22 and moves the sleeve against the pressure of spring 2| asthe rod l3 moves downwardly to actuate the camera shutter. During thismovement the triggel" button slides down while the rod ends 3| and 32engage the sleeve 20 and finally these ends 3| and 32 snap over theupper edge of the sleeve as shown in Fig. 6. As soon as the trigger isreleased the spring 2| will cause the trigger i! to move upwardly andthe sleeve moves upwardly under the impulse of spring 2|. However, sincethe two arms 3| and 32 rest against the outside of the push button whenthe shoulder 18 passes between these arms, the arms may snap between theshoulder |8 and the top wall 40 of the sleeve 22. One rod has reachedthis position in both Figs. 2 and 7. If the operator should forget andagain depress the trigger IS the rod between the shoulder |8 and thewall 40 of the sleeve 22 would serve as a latch element and wouldprevent the trigger from being moved downwardly a suifioient distance tomake an exposure. The operator would be, therefore, automaticallynotified that film has not been wound. By turning the winding key 4|(shown in Fig. 2) the key post I3 is turned and with it the cam l5. Thiscam is so arranged that it will strike first one arm 21 and then thesecond arm 28, thereby moving first arm 3| and, second, arm 32 away froma locking position with respect to the trigger. It is always necessaryto turn the Winding key 4| more than to wind an exposure length of filminto place.

Assuming that the trigger locked with only the arm 32 in latchingposition as shown in Fig. 2, when the operator turns the winding key 4|so that the arm 32 is moved away from the trigger the arm willimmediately snap down into its Fig. 3 position. This is caused by thetension or distortion placed in the rod when it is moved upwardly by thespring 2| after the preceding exposure.

It is, of course, possible that both arm 3| and 32 will simultaneouslylie in the same latching position. If so, one after the other will bereleased by Winding film in the above-described manner.

Another-embodiment of my invention is shown in Fig. 9 in which the rodI26 is shown with an end |32 so mounted that it may distort rod I26 byraising it rather than by twisting as in Fig. 8. This requires a chamber6 somewhat deeper so a bearing I36 will permit such flexing, thisbearing being generally rectangular as shown.

One of the advantages of the devices described above is that they willoperate regardless of the position in which the winding key handle 4| isleft after an area of film has been wound into place. Thi is truebecause a complete locking of the trigger can take place when only onearm is in a latching position. Consequently, if the film should be woundleaving the cam I5 .in the Fig. 3 position, this arm would prevent thearm 32 from latching the trigger but, in any event, the arm 3| would beleft in a position in which it could do the latchin alone. On the otherhand, if the film winding ceases with the cam in the Fig. 5 position,both arms 3| and 22 may be in a latching relationship to the trigger |6since the spring 29 will draw both these arms toward the trigger.

With the preferred form of slide members 25 and 26 made of non-roundwire, such as square wire, it is a very simple matter to hold one end ofthe arm against turning so that when the arm 3| or 32 moves upwardlywith the trigger as shown in Fig. 7, it will at the same time put alight twist or tension in the rod so that, as soon as the arm 3| or 32is released from its latching position by winding the film, the arm willsnap downwardly into the position shown in Fig. 4 about the outside ofthe sleeve 22 which will hold the arms out of locking engagement withthe trigger until the trig er is depressed to a shutter actuating extentas indicated in Fig. 6.

It is usually only necessary to move an arm 3| or 32 a comparativelysmall extent, as for instance the 10 which I have indicateddiagrammatically in Fig. 8. It is of course desirable to have these armswork with extremely light tension because, otherwise, a correspondinglyheavier spring 2| would be required to normally hold the sleeve in itsuppermost position. It is of course obvious that the slide members couldbe made of other materials, but wire having one or more fiat sides isdesirable because it makes the latch more positive in its trigger andsleeve engagement. Round wire flattened at the latch end may be used.

It will be noticed that in the present embodiment of my invention thetrigger latching members do not require a pivotal mount as in the firstembodiment of my invention and that they are of such a constructionthat, if desired, the camera wall 2 can be made of suitable moldedmaterials so that the supports for the rods 25 and 26 can be not onlymade extremely inexpensively but they can be.so made that the cost ofassembly is comparatively small. Moreover, while I have shown the coverplate 4 to enclose a relatively small area 6, this area is somewhatexaggerated in the drawing and the construction can actually be made sothat the camera is only a very little wider than a camera omitting thedouble exposure prevention feature; This is at least partiallyaccomplished by providing a forming 45 around the shutter trigger 46which isof sufliclent depth to permit the rotative movement of the arm32 about the rod 26 to accomplish the locking result above outlined.

While I have described a second preferred embodiment of my invention, itis obvious that the parts can be made slidable as above describedutilizing other shapes and forms, and I contemplate as within the scopeof my invention all such forms as may come within the appended claims.

I claim:

1. A double exposure prevention device for cameras comprising, incombination, a camera, a film winding key post carried thereby, a cam onthe key post, a shutter trigger, a collar slidably mounted on andencircling the trigger and movable to and from a raised position ofrest, a

spring nonmally holding the collar in one position, a pair of resilientslidable members each having an arm at both ends, the arms at one endengaging the cam on the film winding key post and the arms on the otherend positioned to engage the trigger and collar, a slideway carried by acamera wall for each slidable member including means for guiding saidslidable members for longitudinal movement, means for preventingrotational movement of portions of each slidable member spaced from thetrigger, whereby said trigger and sleeve engaging arms may be held in anormal position of rest against the camera wall, said arms being movablefrom the normal position of rest and being flexed by engaging and movingwith the trigger and collar as the trigger is released after an exposureand the collar moves to its position of rest, said winding key postmoving said trigger and sleeve engaging ends from the trigger and sleevethrough movement of the cam whereby the flexed arms may snap back totheir normal position of rest against the camera wall and the triggermay be again depressed.

2. A double exposure prevention device for cameras comprising, incombination, a camera, a film winding key post carried thereby, a cam onthe key post, a shutter trigger, a collar slidably mounted on andencircling the trigger and movable to and from a normal elevatedposition, a spring normally holding the collar in one position, a, pairof resilient slidable members each having an arm at both ends, the armsat one end engaging the cam on the film winding key postand the arms onthe other end positioned to engage the trigger and collar, a slidewayfor each slidable member for guiding it longitudinally and means forpreventing a flexing movement of that portion of the slidable memberspaced from the trigger, whereby said trigger and collar engaging armsmay be held in a normal position engaging the outside of the collar inits normal position, said arms being movable from the normal positionand being flexed by engaging and moving with the trigger and collar asthe trigger is released after an exposure, said slideway including asecond support for each slidable member positioned adjacent the triggerand sleeve in which the slidable members may both turn and slide fordefinitely positioning the slidable members with respect to the windingkey post, said winding key post moving said trigger and collar engagingends from the trigger and collar through movement of the cam whereby theflexed arms may snap back to their normal position and the trigger maybe again depressed.

3. The combination called for in claim 1 in which the slidable membersare formed of a nonround rod having a straight portion from which thearms for engaging the key post and winding key cam are bent at rightangles to the straight portion of the rod.

4. In a double exposure prevention device for cameras having walls, afilm winding key post, and a shutter trigger, the combination with saidwinding key post, of a cam carried thereby, a collar slidably mounted onthe trigger, mechanism for operatively connecting the winding key P stand trigger comprising a pair of slidable rods each rod including offsetarms, one for engaging the key post cam and the other for engaging thetrigger and the collar slidably mounted thereon, said trigger includinga shoulder, a, spring normally pressing the collar towards the shoulderon the trigger, a spring means for moving the offset arms towards thecam at one end and the trigger and collar at the other end, wherebyeither or both slidable rod arms may engage the trigger beneath theshoulder and may engage the collar adjacent thereto forming a latchpreventing effective movement of the trigger for operating the shutter,and whereby a turning movement of the cam in winding film may slide therods to release the trigger after a film has been wound by the key post.

5. A combination according to claim 4 characterized by said cam lying ina plane and means adjacent the cam for retaining the offset arms in theplane of the cam whereby either or both offset arms may be moved by saidspring into contact with said cam.

6. A combination according to claim 4 in which the slidable rods areenclosed in a housing having walls, the walls of which prevent materialflexing of the ofiset arms adjacent the cam, said walls being spacedabout the trigger to permit the flexing of the offset arms adapted toengage the trigger and sleeve.

'7. A combination according to claim 4 in which all the offset arms ofthe slidable rods normally lie fiat against a camera wall, said armsadjacent said cam being held against movement and said arms adjacentsaid trigger being permitted to distortional movement from their normalposition of rest.

8. A combination in accordance with claim 4 in which each slidable rodis slidably mounted and retained against rotative movement near one endthereof whereby tension may be stored in said rod through the triggerand collar moving one offset arm through engagement therewith, said camsliding said arm to release the trigger and collar permitting thestored-up energy in said arm to move from its contact with the triggerwhen released from its position between the trigger and collar.

9. A double exposure prevention device for cameras comprising, incombination, a, camera, a film winding key post carried thereby, a camon the key post, a shutter,- a trigger having a shoulder thereon andmovable to and from a position for actuating the shutter, a collarslidably mounted on and encircling the trigger, a spring normall holdingthe collar in a position spaced from the shoulder when said trigger andcollar are in a normal position of rest, a pair of resilient slidablemembers each having a cam engaging portion and a portion for engagementwith the collar and trigger and forming a means for restraining movementof the trigger when said portion lies between the shoulder and collar, aslideway on the camera wall for guiding the slidable members throughlimited movement to and from the cam and trigger and in which theslidable members tend to lie with the portions for engaging the triggerand collar substantially flat on the camera wall due to the resiliencyof said slidable members, spring means for moving the slidable memberstoward the cam on the key post, said cam moving the slidable membersagainst the action of said spring and being adapted to disengage theportions for engaging the trigger and collar from the locking engagementtherebetween.

10. A double exposure prevention device for cameras comprising, incombination, a camera, a film winding ke post carried thereby, a cam onthe key post, a shutter, a trigger having a shoulder thereon and movableto and from a position for actuating the shutter, a collar slidablymounted on and encircling the trigger, a spring normally holding thecollar in a position spaced from the shoulder when said trigger andcollar are in a normal position or rest, a pair of resilient slidablemembers each having a cam engaging portion and a portion for engagementwith the collar and trigger and forming a means for restraining movementof the trigger when said portion lies between the shoulder and collar, aslideway on the camera wall for guiding the slidable members throughlimited movement to and from the cam and trigger and in which theslidable members tend to lie with the portions for engaging the triggerand collar substantially hat on the camera wall due to the resiliency ofsaid slidable members, spring means for moving the slidable memberstoward the cam on the key post, said cam moving the slidable membersagainst the action of said spring and being adapted to disengage theportions for engaging the trigger and collar from the restrainingengagement therebetween, the cam on the key post extending from the keypost through less than 180 degrees whereb operation of the key post andcam may operate first one slidable member and then the other slidablemember enabling one of the portions of the two slidable members to bedisengaged from the trigger and collar in advance of the other.

11. A double exposure prevention device for cameras comprising, incombination, a camera, a film winding key post carried thereby, a cam onthe key post, a shutter, a trigger having a shoulder thereon and movableto and from a position for actuating the shutter, a. collar slidablymounted on and encircling the trigger, a spring normally holding thecollar in a position spaced from the shoulder when said trigger andcollar are in a normal position of rest, a pair of resilient slidablemembers each having a cam engaging portion and a portion for engagementwith the collar and trigger and forming a means for restraining movementof the trigger when said portion lies between the shoulder and collar, aslideway on the camera wall for guiding the slidable members throughlimited movement to and from the cam and trigger and in which theslidable members tend to lie with the portions for engaging the triggerand collar substantially flat on the camera wall due to the resiliencyof said slidable members, spring means for moving the slidable memberstoward the cam on the key post, said cam moving the slidable membersagainst the action of said spring and being adapted to disengage theportions for engaging the trigger and collar from the restrainingengagement therebetween, said portion of each slidable member beingmoved from between the trigger shoulder and collar whereby theresiliency of the slidable member may cause said portion of thedisengaged slidable member to snap down against the camera wall uponbeing moved by the cam to release its restraining movement effect uponthe trigger.

12. A double exposure prevention device for cameras comprising, incombination, a camera, a film winding key post carried thereby, a cam onthe key post, a shutter, a trigger having a shoulder thereon and movableto and from a position for actuating the shutter, a collar slidablymounted on and encircling the trigger, a spring normally holding thecollar in a, position spaced from the shoulder when said trigger andcollar are in a normal position of rest, a pair of resilient slidablemembers each having a cam engaging portion and a portion for engagementwith the collar and trigger and forming a means for restraining movementof the trigger when said portion lies between the shoulder and collar, aslideway on the camera wall for guiding the slidable members throughlimited movement to and from the cam and trigger and in which theslidable members tend to lie with the portions for engaging the triggerand collar substantially fiat on the camera wall due to the resiliencyof said slidable members, spring means for moving the slidable memberstoward the cam on the key post, said cam moving the slidable membersagainst the action of said spring and being adapted to disengage theportions for engaging the trigger and collar from the locking engagementtherebetween, said trigger and collar being adapted to pass through thecamera wall upon actuating the shutter a suflicient extent for a portionof the slidable member to engage only the trigger when the latter is ina fully depressed shutter actuating position whereby said portion of theslidable member may, upon return movement of the trigger and collar,enter between the shoulder and trigger to prevent a shutter actuatingmovement of the trigger, said cam on the key post being adapted torelease such movement restraining engagement.

MILLER R. HUTCHISON, JR.

